Process for crimping cellulose triacetate fibers



Feb. 27, 1962 .1. R. WYLDE ETAL PROCESS FOR CRIMPING CELLULOSE TRIACETATE FIBERS Filed Aug. 29, 1957 I If I) III F IG fiN Ql/l I: ll 7 Ad ml 0 f nited States Patent 3,022,545 PROCESS FOR CRIMPING CELLULOSE TRIACETATE FIBERS Joseph Rowland Wylde and James Gordon Napier Drewitt, both of Spondon, near Derby, England, assignors to British Celanese Limited, a corporation of Great Britain 'Filed Aug. 29, 1957, Ser. No. 681,029 Claims priority, application Great Britain Sept. 6, 1956 9 Claims. (Cl. 19-66) This invention relates to the treatment of textile fibres, particularly fibres of cellulose acetate of high acetyl value, e.g. acetyl value above 59% calculated as acetic acid, and is especially concerned with the treatment of yarns and like textile products, e.g. continuous filament tows and staple fibre slivers, for the purpose of imparting crimp or waviness to the fibres thereof. For convenience cellulose acetates having acetyl values above 59% are hereinafter referred to as cellulose triacetates.

U.S. application S. No. 644,442, filed March 7, 1957,

discloses that the effect of treating fabrics of cellulose triacetates by heat, whether by dry heat or with steam, for the purpose of increasing the safe ironing temperature thereof and improving their dimensional stability, can be greatly accentuated by the presence in the material of a carboxylic ester of a dior polyhydric alcohol and especially by the presence of diethylene glycol diacetate. It has now been found that the use of heat in the presence of these agents, particularly the use of steam, upon textile fibres of cellulose triacetate which are being crimped, has the effect of imparting a high degree of permanence to the crimp and therefore to the resulting voluminosity and wool-like handle of textile materials made from the fibres.

According to the present invention, therefore, a yarn or like textile material containing fibres of a cellulose triacetate is subjected. while the fibres are in a crimped condition and in the presence of a carboxylic ester of a dior polyhydric alcohol, to the action of heat, particularly the action of steam, so as to increase the permanence of the crimp imparted to the fibres. In order to subject the materials to the action of steam, it is desirable that the agent employed should be water-miscible and applied in aqueous solution, and the material subjected to heat so as to generate the steam from the aqueous solution. Thus, a continuous filament yarn or tow may be passed through a bath containing an aqueous solution of diethylene glycol diacetate and then directly to the feed rollers of a heated stuffer-box of the kind described in U.S. Patent No. 2,763,898, whereby the material is forcedinto one end of a confined passage, from the other end of which its emergence is strongly resisted so as to subject the fibres to crimping pressure in said confined passage, the fibres being heated while they are in said passage by supplying heat to some or all of the boundaries of said passage and thence to the fibres. Alternatively, however, the material may be impregnated with the ester either directly or in aqueous solution and subjected in the stuffer-box to the action of steam supplied to the interior of the stutter-box under pressure.

While diethylene glycol diacetate has been found very eifective for the purposes of the present invention, other carboxylic esters, particularly C to C, fatty acid esters, of dior polyhydric alcohols may be employed, for example other C, to C fatty acid esters of diethylene glycol, dipropylene glycol, or glycerol, e.g. diethylene glycol monoacetate, dipropylene glycol diacetate, glycerol diacetate and glycerol triacetate. Again alkylether-esters of dior polyhydric alcohols, particularly C to C,-alkylether C to C fatty acid esters may be used, for example diethylene glycol monoethyl-ether acetate. Preferably the ester is one having a boiling point 'of at least 190 or 200 C. The proportion of the ester applied to the fibres may vary within wide limits, for example from 10 to 30% based on the weight of the material, but smaller proportions, e.g. down to 5%, or larger proportions, e.g.' up to 60% may be used. In the case of using, as an aqueous liquid, triacetin or other swelling, softening, or plasticising agent which is not miscible with water in convenient proportions, an addition of a suitable volatile watermiscible liquid may be made in order to render the aqueous liquid homogeneous; for instance methyl, ethyl or isopropyl alcohol may be used. Thus in the case of triacetin a suitable padding liquid may consist of a mixture of water, triacetin and isopropyl alcohol containing 300 g.p.l. of triacetin and 300 g.p.l. of isopropyl alcohol.

The preferred method of crimping the fibres is by the stutter-box method referred to above. Where a heavy material is treated, such as a staple fibre sliver or a continuous filament tow which may have a total denier, uncrimped, of up to 100,000 or more, the crimped and treated product emerging from the stufiEer-box may be collected in a 'coiler-can or like container. Lighter materials of up to say 10,000 denier, such as may subsequently be used or directly converted into continuous filament or staple fibre yarn or, as in the case of a'roving, may be drafted before being finally twisted into a yarn, are preferably collected by a suitable winding or twisting-andwinding device. In this case, suitable provision should be made for co-ordinating the rate at which the material is forced into the stufienbox with the rate at which the crimped and treated product is drawn out and fed to the collecting device, and with the quantity of material in the stutter-box so as to ensure that the material has a sufficient residence time in the stufier-box and that the product is not subjected before or during winding to undue tension which might, being applied immediately after the crimping and setting operation, nullify the crimp imparted.

Instead of using a stutter-box for imparting the crimp, other methods of crimping may be employed. Thus the textile material may be passed through crimping rollers having gear teeth formed thereon to impart crimp to the fibres of the material, the fibres being subjected to the heat treatment during their passage through the rollers and/or after their passage, while the fibres are substantially tensionless and still in a crimp condition. Or again, the fibres may be subjected to heat treatment while distorted by means of co-operating racks, toothed belts, sets of interdigitating pins or like means. Yet again, the yarn or the like containing the fibres may be subjected to a temporary twisting operation (e.g. false-twist) the distortions imposed upon the fibres by such twist being set in the fibres by theheat treatment in accordance with the present invention and being retained in the fibres after the twist has left the product.

After crimping, the yarn or like material containing the crimped fibres may be washed to remove the ester or other swelling agent, subjected to appropriate textile treatments, e.g. twisting, cutting or otherwise converting into staple fibres which are then spun into yarn, weaving, knitting, netting and the like, and at any stage in such textile treatments may be dyed or otherwise finished as desired. The treatment of the invention, indeed, appears to facilitate subsequent dyeing of the material, for example with disperse dyes from conventional aqueous baths. If desired, the crimped fibres may be subjected to textile yarnor fabric-forming operations up to the point of being dyed, without intermediate washing, use being made of the ester or other swelling agent on the material to facilitate dyeing as described in co-pending U.S. application S. No. 647,488, filed March 21, 1957, and now abandoned.

The textile fibres of triacetate treated in accordance with the invention may be made by any of the methods set out in US. application S. No. 644,442, referred to above.

The following are given as examples of the manner in which the process according to the invention may be carried out.

Example] A tow of 6,000 continuous filaments of cellulose acetate of 61% acetyl value, each filament being of 3 denier so as to give a total denier of about 18,000 is passed through a bath containing a 300 g.p.l. aqueous solution of diethylene glycol diacetate and then through squeeze rollers so as to leave on the tow about 55% of its weight of the solution. The tow is then passed directly to the feed rollers of a heated stutter-box of the kind described in US. Patent No. 2,763,898 whereby the material is forced into one end of a confined passage from the other end of which its emergence is strongly resisted so as to subject the filaments to crimping pressure in said confined passage. Electrical heating elements are provided round the walls of the confined passage, and current is supplied to said elements so that the walls of the passage are heated and supply heat to the filaments. The tow emerging from the passage is collected in a coiler-can. It is washed to remove the diethylene glycol diacetate and may then be either fed in a wet condition to a staple fibre cutter, or first dried and then fed to such a cutter or converted by drafting into a staple fibre product.

Example 11 A number of continuous filament yarns of cellulose triacetate, each comprising 40 filaments and each having a total denier of 150 are passed, as in Example I, together through a bath containing a 200 g.p.l. solution of diethylene glycol diacetate, and are squeezed to leave about 60% ofsolution on the yarns. After leaving the squeeze rollers the yarns are fed separately to the nip rollers of a corresponding number of stutter-boxes each of the type in which a vertical cylinder is fed from below by its nip rollers and is furnished with a loosely fitting weighted plunger entering it from above to exert pressure on the filamentary mass within the cylinder. The cylinder is furnished with a steam jacket, the steam supplied to the jacket being allowed to enter the cylinder and come into contact with the filamentary material through a regular pattern of narrow radial passages leading from the'jacket to the cylinder. The resulting crimped yarn emerges upwards through the clearance between the plunger and the cylinder and is led to a pair of output nip rollers whose speed is controlled, in relation to that of the input rollers of the stutter-box, by the height of the plunger so as to maintain a substantially uniform quantity of filamentary material within the stutter-box. From the output rollers the crimped product is led to a winding device of the surface-drive type, having a package-driving roller which is geared to the output nip rollers so as to rotate at a somewhat lower peripheral speed than said rollers and to wind up the material substantially without tension into a cheese or like package. The crimped yarn is washed in package form.

Example 111 Yarn is treated as in Example II except that the solution of diethylene glycol diacetate is replaced by a saturated solution (7%) of triacetin. In this case it is desirable to wash the resulting package first with a 30% aqueous solution of isopropyl alcohol and then with water.

Example IV Two 200 denier yarns of cellulose triacetate, each :omprising 52 filaments are drawn over-end from two cones or like packages by means of a pair of feed rollers driven at a speed of about 28 yards per minute and feeding the yarns together through a bath containing an aqueous mixture of water, triacetin and isopropyl alcohol containing 300 g.p.l. of triacetin and 300 g.p.l. of isopropyl alcohol. The yarns leave the bath by a pair of squeeze rollers and are then led together upwards through a vertical tube 12 inches in length externally furnished with electrical heating elements and suitably lagged. Emerging from the heating tube the yarns pass in engagement with a false-twisting spindle driven at 33.000 r.p.m. so that the two yarns are temporarily twisted together, between the squeeze rollers and the spindle, with a false twist of the order of 32 turns per inch to the resulting product. On leaving the false-twisting device the yarns pass together through a pair of draw rollers driven at the speed of 28 yards per minute. They are then passed one on each side of a waisted separating guide and are led to separate constant speed take-up devices by which they are wound at a speed of 24 yards per minute into Example V A 300 denier yarn of cellulose triacetate made up of 60 continuous filaments is drawn through an aqueous solution of 300 g.p.l. of dipropylene glycol diacetate and is passed to a crimping machine of the type having a rotary head similar in character to that of a circular knitting machine except that the needle-like elements do not reciprocate vertically but are stationary in a raised position, while the horizontal sinker-like elements, which are radially movable under the influence of a fixed sinker cam, are of somewhat simplified form, presenting a vertical edge which is caused to intermesh with the needlelike elements by the radial movement of the sinker-like elements. The yarn is fed between the two type of ele ments at a fixed point where they are separated and is drawn part way round the circle by the rotation of the elements, being forced into a crimped form by the interengagement of the elements in the course of their progress round the circle. The yarns, while so engaged and in a crimped and distorted form, are subjected to the action of infra-red lamps by which they are heated and by which the filaments thereof are set into crimped form. The crimped yarn is discharged at another fixed point round the circle by the disengagement of the needle-like and sinker-like elements and is drawn away to be Wound up without tension into a package which may be washed as in the previous examples.

The following description is given of the forms of apparatus employed in carrying out the foregoing examples, the description being illustrated by the accompanying drawings, in which:

FIGURE 1 is a diagrammatic side elevation of an apparatus employing a heated stuffer-box of the kind described in Example I;

FIGURE 2 is a similar view of the type of apparatus employed in Examples II and III;

FIGURE 3 shows the form of apparatus used in Example IV, and

FIGURE 4 that of Example V.

In FIGURE 1 the continuous filament tow 6 is fed into the bath 7 by means of feed rolls 8 and is withdrawn by squeeze rolls 9 and forwarded to the nip rolls 11 of the stutter-box 12, whichis heated by means of electrical heating elements 13, extending round the sides of the box (not shown) as well as over the back, as shown, the elements being supplied with current by leads 14. The emerging crimped product 15 is received into coiler can 16.

In FIGURE 2 the nip rolls 11 feed the yarn 18 upwards into the cylindrical stutter-box 19 surrounded by a steam jacket 21 which communicates by radial passages 22 with the interior of the box 19. The weighted plunger 23 actuates a control mechanism 24 which controls the speed of the output rolls 25 and of the drive roll 26 which rotates the package 27 by surface contact, the yarn 18 being traversed to and fro along the package by a traverse guide 28.

In FIGURE 3 the yarns 18 are drawn from the package 29 by the feed rolls 8 and are fed upwards by the squeeze rolls 9 through the heated tube 31 which is provided with heating elements 32 and lagging 33. The false-twist spindle 34 is driven by means of belt 35. The draw rolls 36 feed the yarns 18 past the waisted separating guide 37 on their way to the take-up devices 26-28.

In FIGURE 4, which is a plan view of the crimping head, 41 represents the vertical needle-like elements and 42 the horizontal, radially extending sinker-like elements.

- The yarn, after passing through-both 7 and between rolls 9, is fed at the point 43 where the elements are separated and extends three parts round the circle to the point 44 during the course of which travel the elements 42 move inwards to interengage with elements 41 over the zone covered by the infra-red lamps 45, the sinkers being actuated by a single cycle cam within the cam box 46.

Having described our invention, what we desire to secure by Letters Patent is:

1. Process for imparting crimp of a high degree of permanence to the cellulose tricetate fibres of a strand containing such fibres, which comprises bringing the said fibres of said strand into a crimped condition and heating the strand While it carries an agent consisting essentially of diethylene glycol diacetate and water.

2. A process according to claim 1 wherein the strand containing cellulose triacetate fibres is impregnated with the aqueous solution of diethylene glycol diacetate, the fibres thereof are then brought to a crimped state, and the strand is heated.

3. Process according to claim 1 wherein the fibres of the strand are compression crimped by forcing the strand into a confined space from which its emergence is restricted.

4. Process according to claim 3 wherein the strand is passed through a bath consisting of diethylene glycol diacctate and water on its way to the confined space and the heating of the strand is effected by suppling heat to the walls of the confined space.

5. A process according to claim 2 wherein the crimping of the fibres is effected by applying a temporary twist to the strand and the latter is heated while so twisted.

6. A process according to claim 3 wherein the strand is a yarn of continuous filaments of cellulose triacetate.

7. A process according to claim 3 wherein the strand is a tow of continuous filaments of cellulose triacetate.

8. Process for imparting crimp of a high degree of permanence to the cellulose triacetate fibres of a strand containing such fibres, which comprises mechanically crimping said strand and heating the crimped strand while it carries an aqueous solution of a carboxylic ester of a. polyhydric alcohol.

9. Process according to claim 8 wherein the strand is compression crimped by being forced into a confined space from which its emergence is restricted, heating of the strand being effected by supplying heat to the walls of the confined space.

References Cited in the file of this patent UNITED STATES PATENTS 

1. PROCESS FOR IMPARTING CRIMP OF A HIGH DEGREE OF PERMANENCE TO THE CELLULOSE TRICETATE FIBRES OF A STRAND CONTAINING SUCH FIBRES, WHICH COMPRISES BRINGING THE SAID FIBRES OF SAID STRAND INTO A CRIMPLED CONDITION AND HEATING THE STRAND WHILE IT CARRIES AN AGENT CONSISTING ESSENTIALLY OF DIETHYLENE GLYCOL DIACETATE AND WATER. 